The Lighthill-Whitham-Richards, or LWR, partial differential equation [1]}, [2]}, which was derived 65 years ago, is mimicking hydrodynamic conservation laws. It is the simplest model for a macroscopic traffic flow model
\(\frac{\partial }{\partial t}\rho (t,x) + \frac{\partial }{\partial x}f(t,x) = 0\) 
